Detergents used for washing clothes have conventionally contained detergent builders (detergent aids) such as zeolite, carboxymethylcellulose, or polyethylene glycol for the purpose of improving the washing effects of detergents.
In recent years, detergent compositions have contained polymers as detergent builders in addition to the above various detergent builders.
For example, use of water-soluble copolymers prepared from an unsaturated monocarboxylic acid monomer and an unsaturated polyalkylene glycol monomer and/or a sulfonate group-containing monomer, as detergent builders or the like, is disclosed (refer to Patent Literatures 1 to 4).
In recent years, consumers have been aware of environmental issues, and the performance needed for detergent builders seems to be changing. Specifically, consumers have saved water by using remaining hot water in a bath for laundry, or have chosen detergents effective at a small amount (compacted detergent compositions) to reduce the amount of detergent components discharged in drainage water.
However, laundry using remaining hot water in a bath has a problem of more soil or hard components in the water. Further, a similar problem arises in an area where there is water with high hardness. For the above problem, agents having higher anti-redeposition properties than the conventional properties are required to further suppress redeposition of soil to fibers or the like during washing under high hardness condition.